# Draft California 2012 Integrated Report( 303(d) List/305(b) Report)

# Supporting Information

## Regional Board 6 - Lahontan Region

Water Body Name: | East Walker River, below Bridgeport Reservoir
Water Body ID: | CAR6301001020011204100242
Water Body Type: | River & Stream

DECISION ID | 28615 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Nitrogen
Final Listing Decision: | Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Delist from 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Reason for Delisting: | Applicable WQS attained; reason for recovery unspecified
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Four lines of evidence are available in the administrative record to assess this pollutant. Zero of the samples exceed the water quality objective. Though LOE 27682 indicates one exceedance, this is incorrect because the result was compared to a WQO for a different water body segment (East Walker above the Bridgeport Rez). Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. Four lines of evidence are available in the administrative record to assess this pollutant. One line of evidence documents the data used in the original listing. This listing used a water quality objective that applies upstream of the station where data were collected. The applicable California water quality objective for the segment of the East Walker River downstream of Bridgeport Reservoir is the narrative objective for biostimulatory substances. No biological data are available to assess whether the data used for listing or the later SWAMP samples comply with this objective. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded. No biological data are available to assess whether the data used for listing or the later SWAMP samples comply with this objective.

Line of Evidence (LOE) for Decision ID 28615, Nitrogen | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 27682
Pollutant: | Nitrogen
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 1
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | Nine samples collected by the U.S. Geological Survey in 2000 and 2001 had a mean concentration of 0.64 mg/L, exceeding the objective. The range of concentrations was 0.109 to 1.32 mg/L.
Data Reference: | Administrative Record of Lahontan RWQCB's 2001-2002 Section 303(d) List Update Process Resolution R6T-2002-0002
SWAMP Data: | Non-SWAMP
Water Quality Objective/Criterion: | The site-specific objective for Total Nitrogen includes an annual average of 0.50 mg/L and a 90th percentile value of 0.80 mg/L (Lahontan Basin Plan Table 3-15). (Note: this objective was used in the original listing. However, it applies to the East Walker River above Bridgeport Reservoir. There is no California numeric objective for nitrogen in the river below the reservoir.)
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Samples were collected at the USGS gaging station below Bridgeport Reservoir.
Temporal Representation: | Nine samples were collected approximately monthly in 2000 and 2001.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | The data were collected and analyzed under USGS quality assurance protocols.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 28615, Nitrogen | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 34531
Pollutant: | Total Nitrogen as N
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | The two samples collected could not be compared to a water quality objective.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There is no site-specific numerical objective in the Lahontan Basin Plan for Total Nitrogen for this segment. The regionwide narrative objective for biostimulatory substances states: "Waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect the water for beneficial uses."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Samples were collected at East Walker River, at CA/NV state line (630EWK001).
Temporal Representation: | Samples were collected on August and November 2007.
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 28615, Nitrogen | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7749
Pollutant: | Total Kjeldahl Nitrogen (TKN)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 16
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey collected 16 quarterly samples under the Region 6 SWAMP program between 2001 and 2005. Concentrations of total Kjeldahl nitrogen ranged from 0.37 to 3.1 mg/L. No associated data on algae or macrophytes were available for assessment of compliance with the objective for biostimulatory substances.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There is no site-specific objective for total Kjeldahl nitrogen. The Lahontan Basin Plan's narrative objective for biostimulatory substances states: "Waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect the water for beneficial uses."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Sixteen quarterly samples were collected between 2001 and 2005.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 28615, Nitrogen | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5036
Pollutant: | Total Nitrogen as N
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 16
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled this segment under the Region 6 SWAMP program, at quarterly intervals between 2001 and 2005. Calculated concentrations of total nitrogen in 16 samples ranged from 0.386 to 3.463 mg/L. No biologiical data were collected for assessment of compliance with the objective for biostimulatory substances.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There is no site-specific numerical objective in the Lahontan Basin Plan for Total Nitrogen for this segment. The regionwide narrative objective for biostimulatory substances states: "Waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect the water for beneficial uses."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Sixteen quarterly samples (two to four samples per year) were collected between 2001 and 2005.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 28795 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Phosphorus
Final Listing Decision: | Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Delist from 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Reason for Delisting: | Flaws in original listing
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for removal from the section 303(d) list under section 4.1 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status. Three lines of evidence are available in the administrative record to assess this pollutant. One line of evidence documents the data used in the original listing. This listing used a water quality objective that applies upstream of the station where data were collected. The applicable California water quality objective for the segment of the East Walker River downstream of Bridgeport Reservoir is the narrative objective for biostimulatory substances. No biological data are available to assess whether the data used for listing or the later 2012 SWAMP samples comply with this objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification for removing this water segment-pollutant combination from the section 303(d) list. This conclusion is based on the staff findings that: 1. The2010 SWAMP data used do not satisfy the data quality requirements of section 6.1.4 of the Policy due to an error in the SWAMP QAPP regarding holding times for total phosphorus samples. The 2012 SWAMP data met the appropriate holding times. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the full range of seasonal and annual variation in streamflows and constituent concentrations expected in streams of the Lahontan Region. Water quality in this segment is also affected by the timing of releases from Bridgeport Reservoir. 3. The original listing was on the basis of one annual average datapoint in violation of a water quality objective that does not actually apply to this segment. No biological data are available to assess whether the 11 monthly samples involved in the original listing or the 15 quarterly SWAMP samples for total phosphorus comply with the narrative objective for biostimulatory substances. The data cannot be assessed using Table 4.1 of the Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 28795, Phosphorus | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 34530
Pollutant: | Phosphorus
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | The annual average for 2007 exceeds the water quality objective for Total Phosphorus. Total Phosphorus was calculated by summing Orthophosphate as P and Phosphorus as P data. Phosphorus as P data were averaged when they were collected on the same day. 2 pairs were summed and then averaged for 2007 before comparing with the Total Phosphorus annual average objective.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | Table 3-15 of the Basin Plan states that the water quality objective for Total P for East Walker River below Bridgeport Reservoir is 0.06 mg/L as an annual average.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Samples were collected at East Walker River, at CA/NV state line (630EWK001).
Temporal Representation: | Samples were collected on August and November 2007.
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 28795, Phosphorus | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 27683
Pollutant: | Phosphorus
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 1
Number of Exceedances: | 1
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey collected monthly samples at the gaging station below Bridgeport Reservoir between April 2000 and February 2001. The mean concentrations of these 11 samples was 0.083 mg/L. The mean annual cocentration in nine USGS samples for 2000 was 0.094 mg/L.
Data Reference: | Administrative Record of Lahontan RWQCB's 2001-2002 Section 303(d) List Update Process Resolution R6T-2002-0002
SWAMP Data: | Non-SWAMP
Water Quality Objective/Criterion: | The site-specific water quality objective used in the 2002 listing of the East Walker River included an annual mean total phosphorus concentration of 0.06 mg/L and a 90th percentile value of 0.10 mg/L. This objective actually applies to a station upstream of Bridgeport Reservoir.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Samples were collected at the USGS gaging station below Bridgeport Reservoir.
Temporal Representation: | Eleven samples were collected monthly between April 2000 and February 2001.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Sampling and analysis were done according to the SWAMP QAPP. However, in July 2009 an error was discovered in the QAPP related to holding times for total phosphorus samples that affects the validity of data for the Lahontan Region The holding time for samples that are not acid-preserved.should be 48 hours rather than 28 days as indicated in the QAPP. "Low level" phosphorus analyses, without acid preservation, are used in the Lahontan Region's SWAMP program. .
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 28795, Phosphorus | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5049
Pollutant: | Phosphorus
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 15
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled the East Walker River under the Region 6 SWAMP program, at quarterly intervals between 2001 and 2005. Concentrations of total P in 15 samples ranged from 0.036 to 0.37 mg/L. No biological data are available for assessment of compliance with the objective for biostimulatory substances.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There are no site specific numerical objectives for phosphorus for this segment. The regionwide narrative objective for biostimulatory substances states: "Waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect the water for beneficial uses."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Fifteen quarterly samples were taken between 2001 and 2005.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 21854 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Boron
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line(s) of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the six samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples, or even less frequent, do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of six samples exceeded the California Notification Level criterion, and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy, and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 16 samples is needed for application of table 3.1. 4. Pursuant to [section 3.11of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 21854, Boron | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7686
Pollutant: | Boron
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled boron under the Region 6 SWAMP program, at quarterly intervals between 2002 and 2005. Boron concentrations in 9 samples ranged from 39 to 178 ug/L. The criterion was not exceeded.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The California State Notification Level criterion for boron is 1000 ug/L.
Objective/Criterion Reference: | Drinking Water Notification and Response Levels: An Overview
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Nine quarterly samples were collected between 2002 and 2005.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout. Boron in this watershed is from natural sources.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 21854, Boron | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 32242
Pollutant: | Boron
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Zero of 2 samples exceeded the California State Notification Level criterion.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | Waters shall not contain concentrations of chemical constituents in amounts that adversely affect the water for beneficial uses.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | The California State Notification Level criterion for boron is 1 mg/L.
Guideline Reference: | Drinking Water Notification Levels and Response Levels
Spatial Representation: | Data was collected at the following station: 630EWK001 East Walker River, below Bridgeport Reservoir.
Temporal Representation: | Samples were collected: 11/8/2007 8/14/2007
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 20785 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Chloride
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples, or those collected less frequently, do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of the 18 samples exceeded the applicable water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 20785, Chloride | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5040
Pollutant: | Chloride
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 16
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled chloride under the Region 6 SWAMP program, at quarterly intervals between 2002 and 2005. Chloride concentrations in 16 samples ranged from 0.58 to 5.35 mg/L. The MCL was not violated.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for chloride is 250 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Sixteen quarterly samples (2 to 4 samples per year) were collected between 2001 and 2005.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 20785, Chloride | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 32229
Pollutant: | Chloride
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total Dissolved
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Zero of 2 samples exceeded the Secondary MCLs.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Secondary Maximum Contaminant Levels (SMCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The SMCL for chloride is 250 mg/L.
Objective/Criterion Reference: | Secondary Maximum Contaminant Levels and Compliance. CCR title 22 section 64449.
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data were collected at the following station: 630EWK001-East Walker River, below Bridgeport Reservoir.
Temporal Representation: | Samples were collected on the following dates: 8/14/2007 11/8/2007
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 22051 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Dissolved oxygen saturation
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Three of the 11 samples exceed the water quality objective for COLD. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly, or less frequent, samples do not capture the diel, seasonal and annual variability expected in streamflows and dissolved oxygen concentrations in streams of the Lahontan Region. 3. Three of the 11 samples exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy, and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 26 samples is needed for application of table 3.2. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 22051, Dissolved oxygen saturation | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 44403
Pollutant: | Dissolved oxygen saturation
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 5
Number of Exceedances: | 3
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for East Walker River, below Bridgeport Reservoir to determine beneficial use support and results are as follows: 3 of 5 samples exceed the criterion for Oxygen, Saturation.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Water Quality Control Plan for the Lahontan Region's water quality objective states that the dissolved oxygen concentration shall not be less than 80 percent of saturation.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for East Walker River, below Bridgeport Reservoir was collected at 1 monitoring site [ East Walker River, at CA/NV state line]
Temporal Representation: | Data was collected over the time period 8/14/2007-12/26/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 22051, Dissolved oxygen saturation | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5815
Pollutant: | Dissolved oxygen saturation
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Aquatic Life Use: | Fish Spawning
Number of Samples: | 6
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey measured percent saturation of dissolved oxygen quarterly between November 2003 and August 2005 under the Region 6 SWAMP program. Percent saturation in 6 measurements ranged from 88 to 119 percent. The objective was not violated.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Lahontan Basin Plan's narrative objective states that percent saturation shall not be depressed by more than 10 percent and minimum dissolved oxygen concentration shall not be less than 80 percent saturation.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, the East Walker River near state line, was sampled.
Temporal Representation: | Six quarterly measurements were taken between November 2003 and August 2006.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 20788 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Fecal Coliform
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.3 of the Listing Policy. Under sections 3.3 a single line of evidence is necessary to assess listing status. Four lines of evidence, one to evaluate MUN and three to evaluate REC-1, are available in the administrative record to assess this pollutant. LOE ID 34859 is not used in the listing decision because the objective of 40 cfu/ml is more applicable if there is only one sample collected within a 30-day period. The 2012 LOEs were compared to two different water quality objectives to gauge compliance with REC-1. None of the samples exceed the water quality objective for MUN or REC-1. All of the five 2012 samples were evaluated using 2 different but related water quality objectives for fecal coliform. None of the five samples exceed the water quality objective of 40 cfu/100 ml nor did any exceed the water quality objective of 30-day geomean of 20 cfu/100 ml. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and fecal coliform counts in streams of the Lahontan Region. The water quality objective calls for five samples to be collected within a 30-day period. 3. None of six samplesfor MUN and none of the 16 samples for REC-1, exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 20788, Fecal Coliform | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 32253
Pollutant: | Fecal Coliform
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 5
Number of Exceedances: | 0
Data and Information Type: | Not Specified
Data Used to Assess Water Quality: | Zero of the five samples exceeded the Fecal Coliform objective.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The fecal coliform concentration shall not exceed more than 40/100 ml.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | The samples were collected from station 630EWK001 East Walker River, at CA/NV state line.
Temporal Representation: | The samples were collected once a month from August to December 2007.
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 20788, Fecal Coliform | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 34859
Pollutant: | Fecal Coliform
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 5
Number of Exceedances: | 0
Data and Information Type: | Not Specified
Data Used to Assess Water Quality: | Zero of the five samples exceeded the fecal coliform objective.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml. Water Quality Control Plan for the Lahontan Region.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | The samples were collected from station 630EWK001 East Walker River, at CA/NV state line.
Temporal Representation: | The samples were collected once a month from August to December 2007.
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 20788, Fecal Coliform | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5694
Pollutant: | Fecal Coliform
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 6
Number of Exceedances: | 0
Data and Information Type: | Water column surveys (e.g. fecal coliform)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled fecal coliform bacteria under the Region 6 SWAMP between 2003 and 2005. Bacteria counts in five of six samples were estimated values, and the count in one sample was below the detection level. The objective was not violated.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Lahontan Basin Plan's water quality objective for coliform bacteria states: "Waters shall not contain concentrations of coliform organisms attributable to anthropogenic sources, including human and livestock waste. The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml, nor shall more than 10 percent of all samples collected during any 30-day period exceed 40/100 ml. The log mean shall ideally be based on a minimum of not less than five samples collected a evenly spaced as practicable during any 30-day period. However, a log mean concentration exceeding 20/100 ml for any 30-day period shall indicate violation of this objective even if fewer than five samples were collected."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Six quarterly samples were collected at approximately quarterly intervals between November 2003 and August 2005.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 20788, Fecal Coliform | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5695
Pollutant: | Fecal Coliform
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Water Contact Recreation
Number of Samples: | 6
Number of Exceedances: | 0
Data and Information Type: | Water column surveys (e.g. fecal coliform)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled fecal coliform bacteria under the Region 6 SWAMP program between 2003 and 2005. Bacteria counts in five of six samples were estimated values, and the count in one sample was below the detection level. The objective was not violated.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Lahontan Basin Plan's objective for coliform bacteria states: "Waters shall not contain concentrations of coliform organisms attributable to anthropogenic sources, including human and livestock waste. The fecal coliform concentration during any 30-day period shall not exceed a log mean of 20/100 ml, nor shall more than 10 percent of all samples collected during any 30-day period exceed 40/100 ml. The log mean shall ideally be based on a minimum of not less than five samples collected a evenly spaced as practicable during any 30-day period. However, a log mean concentration exceeding 20/100 ml for any 30-day period shall indicate violation of this objective even if fewer than five samples were collected."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Six samples were collected approximately quarterly between November 2003 and August 2005.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 31898 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Fluoride
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of the two samples exceeded the criteria and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 16 samples is needed for application of Table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 31898, Fluoride | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 32237
Pollutant: | Fluoride
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Zero of 2 samples exceed the MCL for Flouride.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for Fluoride is 2.0 mg/L.
Objective/Criterion Reference: | Maximum Contaminant Levels for organic and inorganic chemicals. CCR
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data were collected at the following station: 630EWK001-East Walker River, below Bridgeport Reservoir.
Temporal Representation: | Samples were collected on the following dates: 8/14/2007 11/8/2007
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 20786 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Iron
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Four lines of evidence, two each to access COLD and MUN, are available in the administrative record to assess this pollutant. None of the samples exceed the freshwater aquatic life criterion or the Maximum Contaminant Level. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of four samples exceeded the applicable water water quality objective or criterion and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy.A minimum of 16 samples is needed for application of table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 20786, Iron | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 44287
Pollutant: | Iron
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for East Walker River, below Bridgeport Reservoir to determine beneficial use support and results are as follows: 0 of 2 samples exceed the criterion for Iron.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Water Quality Control Plan for the Lahontan Region's Objective for Municipal and Domestic Supply uses of inland surface waters states that waters designated as MUN shall not contain concentrations of chemical constituents in excess of the maximum contaminant level (MCL) or secondary maximum contaminant level (SMCL). This is based upon drinking water standards specified in the following provisions of Title 22 of the California Code of Regulations which are incorporated by reference into the Water Quality Control Plan: Table 64431-A of Section 64431 (Inorganic Chemicals), Table 64431-B of Section 64431 (Fluoride), Table 64444-A of Section 64444 (Organic Chemicals), Table 64449-A of Section 64449 (Secondary Maximum Contaminant Levels-Ranges). The maximum contaminant level listed in Table 64449-A for Iron is 0.3 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for East Walker River, below Bridgeport Reservoir was collected at 1 monitoring site [ East Walker River, at CA/NV state line]
Temporal Representation: | Data was collected over the time period 8/14/2007-11/8/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 20786, Iron | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 44286
Pollutant: | Iron
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for East Walker River, below Bridgeport Reservoir to determine beneficial use support and results are as follows: 0 of 2 samples exceed the criterion for Iron.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | All waters shall be maintained free of toxic substances in concentrations which are toxic to, or which produce detrimental physiological responses in, human, plant, animal, or aquatic life (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | The Red Book states that based on field observations principally, a criterion of 1.0 mg/L iron for freshwater aquatic life is believed to be adequately protective (National Recommended Water Quality Criteria 2009).
Guideline Reference: | National Recommended Water Quality Criteria. United States Environmental Protection Agency. Office of Water. Office of Science and Technology
Spatial Representation: | Data for this line of evidence for East Walker River, below Bridgeport Reservoir was collected at 1 monitoring site [ East Walker River, at CA/NV state line]
Temporal Representation: | Data was collected over the time period 8/14/2007-11/8/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 20786, Iron | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5081
Pollutant: | Iron
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled iron under the Region 6 SWAMP program in 2001 and 2002. Total recoverable iron concentrations in 4 samples ranged from 210 to 260 ug/L. The MCL was not violated.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The secondary MCL for iron is 300 ug/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 20786, Iron | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7710
Pollutant: | Iron
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled iron under the Region 6 SWAMP program in 2001 and 2002. Dissolved iron concentrations in two of four samples were estimated values. Dissolved iron concentrations in the remaining samples were samples 29 and 71 ug/L. The criterion was not violated.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The U.S. Environmental Protection Agency's national freshwater aquatic life criterion for iron is a 4-day average of 1000 ug/L.
Objective/Criterion Reference: | National recommended water quality criteria: 2002. EPA-822-R-02-047 Washington, D.C. USEPA
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 21055 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Nitrate/Nitrite (Nitrite + Nitrate as N)
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability in streamflows and constituent concentrations expected in streams of the Lahontan Region. 3. None of 18 samples exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 21055, Nitrate/Nitrite (Nitrite + Nitrate as N) | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5034
Pollutant: | Nitrate/Nitrite (Nitrite + Nitrate as N)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 16
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled this station under the Region 6 SWAMP program between 2001 and 2005. Concentrations of nitrite plus nitrate in 16 quarterly samples ranged from below detection level to 0.42 mg/L. One sample was an estimated value. The MCL was not exceeded.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for nitrite plus nitrate is 10 mg/L expressed "as nitrogen."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Sixteen quarterly samples were collected between 2001 and 2005.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout. Boron in this watershed is from natural sources.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 21055, Nitrate/Nitrite (Nitrite + Nitrate as N) | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 44326
Pollutant: | Nitrate/Nitrite (Nitrite + Nitrate as N)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for East Walker River, below Bridgeport Reservoir to determine beneficial use support and results are as follows: 0 of 2 samples exceed the criterion for Nitrate/Nitrite as N.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The California Maximum Contaminant Level for nitrate + nitrite (as N) that is incorporated by reference in the Water Quality Control Plan, Lahontan Region is 10.0 mg/L (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for East Walker River, below Bridgeport Reservoir was collected at 1 monitoring site [ East Walker River, at CA/NV state line]
Temporal Representation: | Data was collected over the time period 8/14/2007-11/8/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 28248 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Nitrite
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. None of the three samples exceed the California Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy but this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 16 samples is needed for application of table 3.1. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 28248, Nitrite | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 44346
Pollutant: | Nitrite
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for East Walker River, below Bridgeport Reservoir to determine beneficial use support and results are as follows: 0 of 2 samples exceed the criterion for Nitrite as N.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Water Quality Control Plan, Lahontan Basin, Objective for Municipal and Domestic Supply uses of inland surface waters states the following: waters shall not contain concentrations of inorganic chemicals in excess of the limits specified in California Code of Regulations, Title 22, Table 64431-A of section 64431 (Inorganic Chemicals). The maximum contaminant level listed in Table 64431-A for Nitrite as N is 1.0 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for East Walker River, below Bridgeport Reservoir was collected at 1 monitoring site [ East Walker River, at CA/NV state line]
Temporal Representation: | Data was collected over the time period 8/14/2007-11/8/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 28248, Nitrite | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7747
Pollutant: | Nitrite
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 1
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey collected one NO2-N sample under the Region 6 SWAMP program on 6/28/2002. The nitrite concentration was 0.011 mg/L. The MCL was not violated.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for nitrite is 1 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | One sample was collected on 6/28/2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 21806 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Oxygen, Dissolved
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Five of the 20 samples exceed the water quality objective, but the sample frequency is not sufficient to adequately represent the diel, seasonal and annual variability expected in streamflows and dissolved oxygen concentrations in streams of the Lahontan Region. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the diel, seasonal and annual variability expected in streamflows and dissolved oxygen concentrations in streams of the Lahontan Region. 3. Five of twenty samples exceeded the objective and though this exceeds the allowable frequency listed in Table 3.2 of the Listing Policy, staff do not believe the data support listing because of they do not represent the temporal variability of dissolved oxygen in the waterbody. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 21806, Oxygen, Dissolved | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 32270
Pollutant: | Oxygen, Dissolved
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 5
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | One sample was below the 1 day minimum.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The objective from Lahontan Basin Plan Table 3-6 with both cold and spawn beneficial uses shall not be less than a one-day minimum dissolved oxygen concentration of 8 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data were collected at the following station: 630EWK001-East Walker River, below Bridgeport Reservoir.
Temporal Representation: | Samples were collected between August and December 2007
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 21806, Oxygen, Dissolved | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5731
Pollutant: | Oxygen, Dissolved
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Aquatic Life Use: | Fish Spawning
Number of Samples: | 15
Number of Exceedances: | 4
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey measured dissolved oxygen quarterly between 2001 and 2005 under the Region 6 SWAMP program. Dissolved oxygen concentrations in 15 samples ranged from 7.1 to 12 mg/L. Four of 15 samples were below the 8 mg/L minimum concentration.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | For waters designated for the COLD and SPWN beneficial uses the 1- day minimum objective is 8 mg/L (Lahontan Basin Plan Table 3-6)
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, the East Walker River near state line, was sampled.
Temporal Representation: | Fifteen quarterly samples were collected between August 2002 and August 2005.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 21001 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Specific Conductance
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence is available in the administrative record to assess this pollutant. None of the 23 samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and dissolved ion concentrations in streams of the Lahontan Region. 3. None of 23 samples exceeded the water quality objective and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 26 samples is needed for application of table 3.2. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 21001, Specific Conductance | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5050
Pollutant: | Specific Conductance
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 14
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey measured specific conductance under the Region 6 SWAMP program, at quarterly intervals between 2001 and 2005. Fourteen field measurements of specific conductance ranged from 144 to 271 uS/cm. An additional 6 laboratory measurements were taken for samples collected on the same dates as field measurements. Laboratory specific conductance ranged from 151 to 202 uS/cm. The MCL was not exceeded.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for specific conductance is 900 microsiemens per centimeter (uS/cm).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Fourteen quarterly field measurements and 6 laboratory measurements of specific conductance were taken between 2001 and 2005.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 21001, Specific Conductance | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 44383
Pollutant: | Specific Conductivity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 9
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for East Walker River, below Bridgeport Reservoir to determine beneficial use support and results are as follows: 0 of 9 samples exceed the criterion for Conductivity(Us).
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The California Secondary MCL that is incorporated by reference in the Water Quality Control Plan, Lahontan Region for specific conductance is 900 uS/cm (Water Quality Control Plan, Lahontan Region).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data for this line of evidence for East Walker River, below Bridgeport Reservoir was collected at 1 monitoring site [ East Walker River, at CA/NV state line]
Temporal Representation: | Data was collected over the time period 8/14/2007-12/26/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 20771 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Sulfates
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the 9 samples exceed the water quality objective of 250 mg/L SO4 (Secondary MCL) for protection of the MUN use. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 9 samples exceeded the water quality objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 20771, Sulfates | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 32235
Pollutant: | Sulfates
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total Dissolved
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Zero of 2 samples exceeded the Secondary MCLs objective.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Secondary Maximum Contaminant Levels (SMCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The SMCL for Sulfates (SO4) is 250 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
| Secondary Maximum Contaminant Levels and Compliance. CCR title 22 section 64449.
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data were collected at the following station: 630EWK001-East Walker River, below Bridgeport Reservoir.
Temporal Representation: | Samples were collected on the following dates: 8/14/2007, 11/8/2007
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 20771, Sulfates | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5052
Pollutant: | Sulfates
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 7
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled sulfate under the Region 6 SWAMP program between 2003 and 2005. Sulfate concentrations in 7 samples ranged from 5.1 to 23 mg/L. The MCL was not violated.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for sulfate is 250 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
| 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Seven samples were collected approximately quarterly between November 2003 and August 2005.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 20768 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Temperature, water
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. One of the 21 samples exceed the water quality objective., however, sampling frequency was not sufficient to determine the natural seasonal and annual temperature range or the extent to which changes occur due to human activities such as reservoir management (Bridgeport Reservoir). The Lahontan Basin Plan's narrative temperature objective is an antidegradation-based objective that requires that there be no change in temperature in waters designated for the Cold Freshwater Habitat (COLD) beneficial use. The objective does not include specific numerical limits for protection of the COLD use. Listing Policy Section 3.10 contains directions for assessment based on trends in water quality. These directions include requirements to establish specific baseline conditions and specify the influence of seasonal and interannual effects. There are not enough temperature samples to establish baseline conditions (including diel, seasonal, annual and interannual variations in temperature) or to detect declining trends in the temperature regime if such trends exist. Because temperature samples were collected only quarterly, weekly and monthly average data are not available for comparison with guidelines in the scientific literature for the temperature requirements of sensitive aquatic species such as salmonids, as directed in Listing Policy Section 6.1.5.9. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. One of the 21 samples exceeded the objective and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 26 samples is needed for application of table 3.2. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 20768, Temperature, water | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5055
Pollutant: | Temperature, water
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 16
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey measured water temperature at quarterly intervals under the Region 6 SWAMP program between 2001 and 2005. Sixteen water temperature measurements ranged from 0 to 22.5 degrees Celsius. Sampling frequency was not sufficient to determine the natural seasonal and annual temperature range or the extent to which changes occur due to human activities such as reservoir management.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The temperature objective in the Lahontan Basin Plan states: "The natural receiving water temperature of all waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such an alteration in temperature does not adversely affect the water for beneficial uses. For waters designated WARM, water temperature shall not be altered by more than five degrees Fahrenheit ... above or below the natural temperature. For waters designated COLD, the temperature shall not be altered. Temperature objectives for COLD interstate waters and WARM interstate waters are as specified in the 'Water Quality Control Plan for Control of Temperature in The Coastal and Interstate Waters and Enclosed Bays and Estuaries of California' including any revisions."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Sixteen quarterly samples were collected between 2001 and 2005.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 20768, Temperature, water | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 44264
Pollutant: | Temperature, water
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 5
Number of Exceedances: | 1
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | Water Board staff assessed SWAMP data for East Walker River, below Bridgeport Reservoir to determine beneficial use support and results are as follows: 1 of 5 samples exceed the criterion for Water Temperature.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Water Quality Control Plan for the Lahontan Region's water quality objective for all surface waters states the following: The natural receiving water temperature of all waters shall not be altered unless it can be demonstrated to the satisfaction of the Regional Board that such an alteration in temperature does not adversely affect the water for beneficial uses. For waters designated COLD, the temperature shall not be altered.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: | Inland Fishes of California (Moyle 1976) states that for rainbow trout the optimum range for growth and completion of most life stages is 13-21 degrees C (page 129).
Guideline Reference: | Fish introductions in CA: History and impact on native fishes. Davis, CA: University of CA, Davis
Spatial Representation: | Data for this line of evidence for East Walker River, below Bridgeport Reservoir was collected at 1 monitoring site [ East Walker River, at CA/NV state line]
Temporal Representation: | Data was collected over the time period 8/14/2007-12/26/2007.
Environmental Conditions: | Staff is not aware of any special conditions that might affect interpretation of the data.
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 22053 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | pH
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Revised
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. The 2012 LOE is not considered because the normal ambient pH of this waterbody has not been established so it is difficult to determine with certainity if their are exceedances of the objective. Therefore, the previous conclusion remains unchanged, and is as follows: The Lahontan Basin Plan's narrative pH objective is an antidegradation-based objective that requires that there be no change greater than 0.5 pH units in waters designated for the Cold Freshwater Habitat (COLD) or Warm Freshwater Habitat beneficial uses. (A pH range of 6.5 to 8.5 units applies to "all other waters.") Listing Policy Section 3.10 contains directions for assessment based on trends in water quality. These directions include requirements to establish specific baseline conditions and specify the influence of seasonal and interannual effects. One line of evidence is available to support this decision. There are not enough pH samples to establish baseline conditions (including diel, seasonal, annual and interannual variations) or to detect changes in the pH regime due to controllable factors, if such trends exist.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 22053, pH | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 33342
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 0
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | There were 5 samples with pH ranging from 7.7 to 9.5. The normal ambient pH level for this water body is unknown and so it is unknown whether any exceedences occured.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The applicable objective states: "In fresh waters with designated beneficial uses of COLD or WARM, changes in normal ambient pH levels shall not exceed 0.5 pH units." (Lahontan Basin Plan).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Data were collected at the following station: 630EWK001 (East Walker River, at CA/NV state line).
Temporal Representation: | Samples were collected between August and December 2007
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)
Line of Evidence (LOE) for Decision ID 22053, pH | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5043
Pollutant: | pH
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 16
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled pH under the Region 6 SWAMP program, at quarterly intervals between 2002 and 2005. Fifteen field measurements had pH values ranging from 7.8 to 9.7 units. Three measurements exceeded 8.5 units. Five laboratory pH measurements ranged from 7.4 to 8.5 units. However, the 6.5 to 8.5 unit limit does not apply to waters designated for the COLD use.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Lahontan Basin Plan's narrative objectives for pH states: "In fresh waters with designated beneficial uses of COLD or WARM, changes in normal ambient pH levels shall not exceed 0.5 pH units. For all other waters of the region, the pH shall not be depressed below 6.5 nor raised above 8.5 units. The Regional Board recognizes that some waters of the Region may have natural pH levels outside of the 6.5 to 8.5 range. Compliance with the pH objective for these waters will be determined on a case-by-case basis."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Fifteen field measurements of pH were taken quarterly between 2001 and 2005. Five laboratory measurements were taken in samples collected on the same dates as the corresponding field measurements.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 20731 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Sedimentation/Siltation
Final Listing Decision: | Do Not Delist from 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not Delist from 303(d) list (TMDL required list)(2010)
Revision Status | Original
Sources: | Erosion/Siltation | Grazing-Related Sources | Highway Maintenance and Runoff | Upstream Impoundment | Urban Runoff--Erosion and Sedimentation
Expected TMDL Completion Date: | 2019
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: Two lines of evidence are available in the administrative record to assess this pollutant. The original listing was based on best professional judgment regarding a single severe sedimentation incident. Water Board staff did not review quantitative data in connection with the listing. The applicable narrative water quality objective is antidegradation based. The 16 quarterly SWAMP samples are insufficient to establish baseline and trend conditions as required for assessment under Section 4.10 of the Listing Policy. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against removing this water segment-pollutant combination from the section 303(d) list. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the full range of variability in streamflows and constituent concentrations expected in streams of the Lahontan Region. Flows and concentrations in this segment are also affected by the timing of releases from Bridgeport Reservoir. 3. The quarterly SWAMP data are insufficient to establish baseline and trend conditions as required under Section 4.10 of the Listing Policy. 4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 20731, Sedimentation/Siltation | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5051
Pollutant: | Sediment
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 16
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled suspended sediment under the Region 6 SWAMP program, at quarterly intervals between 2001 and 2005, and did load calculations based on concurrent flows. Suspended sediment concentrations in 16 samples ranged from 5 to 28 mg/L. Calculated sediment loads in 8 samples ranged from 0.37 to 23 tons/day. Sampling frequency is insufficient to evaluate compliance with the objective.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Lahontan Basin Plan's narrative objective states: The suspended sediment load and suspended sediment discharge rate of surface waters shall not be altered in such a manner as to cause nuisance or adversely affect the water for beneficial uses.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Sixteen quarterly samples were collected between 2001 and 2005.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 20731, Sedimentation/Siltation | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 4609
Pollutant: | Sedimentation/Siltation
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Not Recorded
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 0
Number of Exceedances: | 0
Data and Information Type: | Not Specified
Data Used to Assess Water Quality: | Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006.
Data Reference: | Placeholder reference pre-2006 303(d)
SWAMP Data: | Non-SWAMP
Water Quality Objective/Criterion: | Unspecified
Objective/Criterion Reference: | Placeholder reference pre-2006 303(d)
Evaluation Guideline: | Unspecified
Guideline Reference: | Placeholder reference pre-2006 303(d)
Spatial Representation: | Unspecified
Temporal Representation: | Unspecified
Environmental Conditions: | Unspecified
QAPP Information: | Unspecified
QAPP Information Reference(s):

DECISION ID | 20736 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Aluminum
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the applicable water quality objective and criterion. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of four samples exceeded the water quality objective or freshwater aquatic life criterion, and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 20736, Aluminum | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5746
Pollutant: | Aluminum
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled aluminum under the Region 6 SWAMP program in 2001 and 2002. Concentrations of dissolved aluminum in four samples ranged from 2 to 18 ug/L. The aquatic life criteria were not exceeded.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The U.S. Environmental Protection Agency acute freshwater aquatic life criterion for aluminum is 750 ug/L, and the chronic criterion is 87 ug/L. Aquatic life criteria are expressed as dissolved metals.
Objective/Criterion Reference: | National recommended water quality criteria: 2002. EPA-822-R-02-047 Washington, D.C. USEPA
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 20736, Aluminum | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5065
Pollutant: | Aluminum
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled aluminum under the Region 6 SWAMP program in 2001 and 2002. Total recoverable aluminum concentrations in four samples ranged from 59 to 110 ug/L. The state MCLs were not exceeded.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The primary MCL for aluminum is 1000 ug/L and the secondary MCL is 200 ug/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 20823 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Antimony
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the aquatic life criteria or the Maximum Contaminant Level. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of four samples exceeded the water quality objective or criteria and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 20823, Antimony | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7716
Pollutant: | Antimony
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled antimony under the Region 6 SWAMP program in 2001 and 2002. Four dissolved antimony samples all had concentrations below the detection limit. Per listing policy Section 6.1.5.5, the criteria are presumed to be attained.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The USEPA Lowest Observed Effect Levels (LOEL) criteria for protection of aquatic life include an acute antimony value of 9000 ug/L, a chronic value of 1600 ug/L and a limit for toxicity to algae of 610 ug/L
Objective/Criterion Reference: | Compilation of Water Quality Goals
| Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 20823, Antimony | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5122
Pollutant: | Antimony
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled antimony under the Region 6 SWAMP program in 2001 and 2002. Four total antimony samples all had concentrations below the detection limit. Per listing policy Section 6.1.5.5, the MCL and CTR standard are presumed to be attained.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The California primary MCL for antimony is 6 ug/L. The California Toxics Rule water and fish consumption standard is 14 ug/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 20955 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Arsenic
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. One of the samples exceeds the California Maximum Contaminant Level (MCL). Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples are inadequate to document variations in arsenic concentrations over time, particularly at a station where flows depend on upstream reservoir releases. 3. One of four samples exceeded the MCL and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 20955, Arsenic | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5030
Pollutant: | Arsenic
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled arsenic under the Region 6 SWAMP program. Dissolved arsenic concentrations in four samples ranged from 2 to 18 ug/L. The CTR standards were not exceeded.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The California Toxics Rule (CTR) standards for protection of freshwater aquatic life are as follows: 4-day average = 150 ug/L 1- hour average = 340 ug/L
Objective/Criterion Reference: | Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout. Arsenic in this watershed is from natural sources.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 20955, Arsenic | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5031
Pollutant: | Arsenic
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 1
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled arsenic under the Region 6 SWAMP program. Concentrations of total arsenic in four samples ranged from 3 to 18 ug/L. One sample exceeded the California MCL.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for arsenic is 10 ug/L (effective November 28, 2008).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. Arsenic in this watershed is from natural sources.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 20956 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Beryllium
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the applicable water quality objective and criteria. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 8 samples exceeded the applicable water quality objective and criteria, and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 20956, Beryllium | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5763
Pollutant: | Beryllium
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled beryllium quarterly in the East Walker River under the Region 6 SWAMP program in 2001 and 2002. Four dissolved beryllium samples had reported concentrations below the detection level. Per listing policy Section 6.1.5.5, the objective is presumed to be attained.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The U.S. Environmental Protection Agency's (USEPA's) freshwater aquatic life criteria for beryllium are as follows: acute (1 hour average) criterion = 130 ug/L; chronic (4 day average) criterion = 5.3 ug/L.
Objective/Criterion Reference: | National recommended water quality criteria: 2002. EPA-822-R-02-047 Washington, D.C. USEPA
| 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 20956, Beryllium | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5068
Pollutant: | Beryllium
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled beryllium under the Region 6 SWAMP program in 2001 and 2002. Four total recoverable beryllium samples had reported concentrations less than the detection limit. Per listing policy Section 6.1.5.5, the MCL is presumed to be attained.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for beryllium is 4 ug/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 22041 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Cadmium
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the California Toxics Rule standards or Maximum Contaminant Level. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of four samples exceeded the applicable standards and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 22041, Cadmium | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5070
Pollutant: | Cadmium
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled cadmium under the Region 6 SWAMP program in 2001 ad 2002. Four total cadmium samples had reported concentrations less than the detection limit. Per listing policy Section 6.1.5.5, the MCL is presumed to be attained.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituent" objective. The MCL for cadmium is 5 ug/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 22041, Cadmium | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7689
Pollutant: | Cadmium
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled cadmium under the Region 6 SWAMP program in 2001 ad 2002. Four total cadmium samples had reported concentrations less than the detection limit. Per listing policy Section 6.1.5.5, the CTR standards are presumed to be attained.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The California Toxics Rule (CTR) aquatic life standards for cadmium are hardness-based. At the hardness levels measured for this station, the acute toxicity standard ranges from 2.29 to 2.75 ug/L and the chronic toxicity standard ranges from 1.45 to 1.65 ug/L.
Objective/Criterion Reference: | Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 21792 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Calcium
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two of evidence are available in the administrative record to assess this pollutant. There are no California or federal standards or water quality criteria for calcium. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. There are no applicable standards or criteria and the data cannot be assessed pursuant to Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 21792, Calcium | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7719
Pollutant: | Calcium
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled the East Walker River under the Region 6 SWAMP program in 2001 and 2002. Concentrations of dissolved calcium in four samples ranged from 17 to 20 mg/L.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There are no state or federal standards or criteria for calcium for the protection of freshwater aquatic life.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 21792, Calcium | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7720
Pollutant: | Calcium
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled the East Walker River under the Region 6 SWAMP program in 2001 and 2002. Concentrations of total calcium in four samples ranged from 16.9 to 18.6 mg/L.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There are no state or federal standards or criteria for calcium for the protection of human health.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 21804 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Chromium (total)
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of four samples exceeded the Califoria Toxics Rule standards or the Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 21804, Chromium (total) | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7695
Pollutant: | Chromium (total)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The USGS sampled the East Walker River under the Region 6 SWAMP program. Concentrations of dissolved chromium in four quarterly samples were all below the detection level. Under Listing Policy section 6.1.5.5 the standards are presumed to be attained.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The California Toxics Rule (CTR) standards for dissolved Chromium VI to protect freshwater aquatic life are11 ug/L ( 4-day average) and,16 ug/L (1 hour average). The CTR standard for Chromium III is hardness dependent. At the hardness levels reported for this station, acute (1 hour average) limits for Chromium III range from 349.71 to 398.82 ug/L. The chronic (4 day average) limits range from 113.41 to 129.37 ug/L.
Objective/Criterion Reference: | Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 21804, Chromium (total) | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5748
Pollutant: | Chromium (total)
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The USGS sampled the East Walker River under the Region 6 SWAMP program. Concentrations of total chromium in four quarterly samples were all below the detection level. Under Listing Policy section 6.1.5.5 the MCL is presumed to be attained.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for chromium is 50 ug/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 21805 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Cobalt
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. There are no California or federal water quality standards or criteria for cobalt. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. There are no applicable standards or criteria. Therefore the data cannot be assessed using Table 3.1 of the Listing Policy.After review of this Regional Board decision, SWRCB staff recommend the decision be approved by the State Board. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 21805, Cobalt | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7700
Pollutant: | Cobalt
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled the East Walker River under the Region 6 SWAMP program in 2001 and 2002. Four samples had concentrations of total recoverable cobalt below the detection level.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There are no state or federal standards or criteria for cobalt for the protection of human health.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 21805, Cobalt | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7698
Pollutant: | Cobalt
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled the East Walker River under the Region 6 SWAMP program in 2001 and 2002. Concentrations of dissolved cobalt in four samples ranged from 0.07 to 0.168 ug/L.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There are no state or federal standards or criteria for cobalt for the protection of freshwater aquatic life.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 20929 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Copper
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 8 samples exceeded the applicable water quality objective and California Toxics Rule standard, and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 20929, Copper | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5069
Pollutant: | Copper
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled copper under the Region 6 SWAMP program in 2001 and 2002. Dissolved copper concentrations in 4 samples ranged from 0.7 to 1.6 ug/L. The CTR standards were not violated.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The California Toxics Rule (CTR) freshwater aquatic life standards for copper are hardness-dependent, At the hardness levels reported for this station, the acute (1 hour average) standard ranges from 8.00 to 9.31 ug/L The chronic (4 day average) standard ranges from 5.60 to 6.42 ug/L.
Objective/Criterion Reference: | Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 20929, Copper | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5076
Pollutant: | Copper
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled copper under the Region 6 SWAMP program in 2001 and 2002. Total recoverable copper concentrations in 4 samples ranged from 1.0. to 1.4 ug/L. The MCLs were not exceeded.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) are applicable under the Lahontan Basin Plan's Chemical Constituents objective. The primary MCL for copper is 1300 ug/L and the secondary MCL is 1000 ug/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 28532 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Dissolved Kjeldahl Nitrogen
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. No biological data are available to determine whether either of the samples exceeds the water quality objective for biostimulatory substances. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. No biological data are available to assess compliance with the objective and the chemical data cannot be assessed using Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 28532, Dissolved Kjeldahl Nitrogen | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7748
Pollutant: | Dissolved Kjeldahl Nitrogen
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 2
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey collected two samples under the Region 6 SWAMP program in August and November 2003. Concentrations of dissolved Kjeldahl nitrogen were 0.9 and 0.38 mg/L. No associated data on algae or macrophytes were available for assessment of compliance with the objective for biostimulatory substances.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There are no site-specific objectives for dissolved Kjeldahl nitrogen. The Lahontan Basin Plan's narrative objective for biostimulatory substances states: "Waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect the water for beneficial uses."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Two samples were collected in August and November 2003.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 21759 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Hardness
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. There are no applicable state or federal standards or criteria. The hardness data assessed fall within the category generally considered "soft". Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy in that only four quarterly samples were available. The minimum sample number requirements of Listing Policy Table 3.2 are not met. 3. There are no applicable standards or criteria. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 21759, Hardness | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7815
Pollutant: | Hardness
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled the East Walker River under the Region 6 SWAMP program in 2001 and 2002. Hardness values in four quarterly samples were 57.69, 67.73, 62.80, and 61.84 mg equivalent CaC03/L. These values are within the range characterizing "soft" water.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There are no state or federal standards or criteria for hardness. Hardness is monitored for purposes such as determination of the applicable criteria and standards for metals whose toxicity is hardness-dependent. The U.S. Environmental Protection Agency's 1986 "Gold Book" includes generally accepted categories of hardness. Calcium and magnesium are the major ions contributing to hardness, and hardness is generally expressed as calcium carbonate. Water with a hardness equivalent to 0-75 mg equivalent CaCO3/L is considered "soft."
Objective/Criterion Reference: | Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 21759, Hardness | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7812
Pollutant: | Hardness
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled the East Walker River under the Region 6 SWAMP program in 2001 and 2002. Hardness values in four quarterly samples were 57.69, 67.73, 62.80, and 61.84 mg equivalent CaC03/L. These values are within the range characterizing "soft" water.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There are no state or federal standards or criteria for hardness. Hardness is monitored for purposes such as determination of the applicable criteria and standards for metals whose toxicity is hardness-dependent. The U.S. Environmental Protection Agency's 1986 "Gold Book" includes generally accepted categories of hardness. Calcium and magnesium are the major ions contributing to hardness, and hardness is generally expressed as calcium carbonate. Water with a hardness equivalent to 0-75 mg equivalent CaC03/L is considered "soft."
Objective/Criterion Reference: | Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 21000 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Lead
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceeded the applicable water quality objective and California Toxics Rule standard. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of eight samples exceeded the applicable water quality objective and California Toxics Rule standard and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 21000, Lead | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5120
Pollutant: | Lead
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled lead under the Region 6 SWAMP program in 2001 and 2002. Concentrations of total recoverable lead in four quarterly samples were below the detection limit. Per listing policy Section 6.1.5.5, the MCL is presumed to be attained.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for lead is 15 ug/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 21000, Lead | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5121
Pollutant: | Lead
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled lead under the Region 6 SWAMP program in 2001 and 2002. Dissolved lead concentrations in four samples included two values below the detection level, one estimated value, and one 0.16 ug/L value. The CTR standards were not exceeded.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The California Toxic Rule (CTR) standards for lead are dependent on hardness. At the reported hardness levels for this station, the acute (1 hour average) standard ranged from 32.06 to 39.33 ug/L. The chronic (4 day average) standard ranged from 1.25 to 1.53 ug/L.
Objective/Criterion Reference: | Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 21876 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Magnesium
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. There are no applicable standards, objectives or criteria for magnesium. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. There are no applicable standards, objectives or criteria for evaluation of the four samples for dissolved magnesium or four samples for total magnesium and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 21876, Magnesium | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7721
Pollutant: | Magnesium
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled the East Walker River under the Region 6 SWAMP program in 2001 and 2002. Concentrations of dissolved magnesium in four samples ranged from 3.7 to 4.32 mg/L.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There are no state or federal standards or criteria for magnesium for the protection of freshwater aquatic life.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 21876, Magnesium | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7722
Pollutant: | Magnesium
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled the East Walker River under the Region 6 SWAMP program in 2001 and 2002. Concentrations of total magnesium in four samples ranged from 3.64 to 4.09 mg/L.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There are no state or federal standards or criteria for magnesium for the protection of human health.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 20789 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Mercury
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of four samples exceeded the applicable water quality objective and criteria, and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 20789, Mercury | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5082
Pollutant: | Mercury
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled mercury under the Region 6 SWAMP program in 2001 and 2002. Mercury concentrations in four samples ranged from less than 0.01 ug/L to 0.01 ug/L. The MCL was not violated.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL tor inorganic mercury is 2 ug/L. The California Toxics Rule water and fish consumption standard for mercury is 0.050 ug/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 20789, Mercury | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5764
Pollutant: | Mercury
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled mercury quarterly in the East Walker River under the Region 6 SWAMP program in 2001 and 2002. Three of four total mercury samples were below the detection level, and one was 0.01 ug/L The criteria were not violated.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The U.S. Environmental Protection Agency (USEPA) freshwater aquatic life criteria (expressed as total mercury) are a 4- day average of 0.77 ug/L and a 1-hour maximum of 1.4 ug/L
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 22052 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Molybdenum
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. There are no applicable water quality standards or criteria. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. There are no applicable water quality standards or criteria and the data cannot be assessed using Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 22052, Molybdenum | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7707
Pollutant: | Molybdenum
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled the East Walker River under the Region 6 SWAMP program in 2001 and 2002. Total recoverable molybdenum concentrations in four samples ranged from 4.4 to 4.9 ug/L.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There are no applicable state or federal standards or criteria for molybdenum for protection of the Municipal and Domestic Supply use.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 22052, Molybdenum | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7709
Pollutant: | Molybdenum
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled the East Walker River under the Region 6 SWAMP program in 2001 and 2002. Concentrations of dissolved molybdenum in four samples ranged from 4.3 to 4.8 ug/L.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There are no state or federal standards or criteria for cobalt for the protection of freshwater aquatic life.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 21190 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Nickel
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of four samples exceeded the applicable objectives and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 21190, Nickel | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5089
Pollutant: | Nickel
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled nickel under the Region 6 SWAMP program in 2001 and 2002. Dissolved nickel concentrations in 4 samples ranged from less than 0.06 ug/L to 0.28 ug/L. The CTR standards were not exceeded.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The California Toxics Rule (CTR) freshwater aquatic life standards for nickel are dependent on hardness. At the hardness levels reported for this station, the acute (1-hour average) standard ranges from 234.01 to 336.75 ug/L. The chronic (4-day average) standard ranges from 32.69 to 37.44 ug/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 21190, Nickel | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5119
Pollutant: | Nickel
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled nickel under the Region 6 SWAMP program in 2001 and 2002. Dissolved nickel concentrations in 4 samples ranged from less than 0.06 ug/L to 0.28 ug/L. The MCL was not exceeded.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for nickel is 100 ug/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 28637 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Phosphate
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. No biological data are available to evaluate whether any of the samples exceeds the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the full range of seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. No biological data are available for assessment of compliance with the water quality objective and the data cannot be assessed using Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 28637, Phosphate | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7792
Pollutant: | Phosphate
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 3
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled the East Walker River under the Region 6 SWAMP program in 2002 and 2003. Concentrations of PO4-P in 3 samples ranged from 0.03 to 1.61 mg/L. No biological data are available for assessment of compliance with the objective for biostimulatory substances.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There are no site specific numerical objectives for phosphate for this segment. The regionwide narrative objective for biostimulatory substances states: "Waters shall not contain biostimulatory substances in concentrations that promote aquatic growths to the extent that such growths cause nuisance or adversely affect the water for beneficial uses."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Three quarterly samples were collected in 2002 and 2003.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 31955 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Salinity
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | New Decision
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. One line of evidence is available in the administrative record to assess this pollutant. None of the five samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy. 3. None of the five samples exceeded the site specific objective for TDS of 145 mg/L which is used to assess the salinity data provided in this data set and this sample size is insufficient to determine with the power and confidence of the Listing Policy if standards are not met. A minimum of 26 samples is needed for application of table 3.2. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should not be placed on the section 303(d) list because it cannot be determined if applicable water quality standards are not being exceeded.

Line of Evidence (LOE) for Decision ID 31955, Salinity | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 34506
Pollutant: | Salinity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 5
Number of Exceedances: | 0
Data and Information Type: | PHYSICAL/CHEMICAL MONITORING
Data Used to Assess Water Quality: | None of the 5 samples exceeded the site specific objective of 145 mg/L.
Data Reference: | RWB6 Trend Monitoring CY2006 CY2007
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The Regional Board will consider site specific adjustments to the objectives for wetlands (bacteria, pH, hardness, salinity, temperature, or other parameters) as necessary on a case-by-case basis. The site specific objective for Total Dissolved Solids at East Walker River, below Bridgeport Reservoir is 145 mg/L and will be used to assess the salinity data provided in this data set.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | Samples collected from the 630EWK001 station.
Temporal Representation: | Samples collected on the following dates: 10/30/2007 11/8/2007 9/18/2007 8/14/2007 12/26/2007
Environmental Conditions: |
QAPP Information: | 2002 QAMP (Quality Assurance Management Plan) for the State of California's Surface Water Ambient Monitoring Program
QAPP Information Reference(s): | Quality Assurance Management Plan for the State of California's Surface Water Ambient Monitoring Program. Sacramento, CA. State Water Resources Control Board. SWAMP. December 2002 (1st version)

DECISION ID | 21807 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Selenium
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two line of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the California Toxics Rule standards or the Maximum Contaminant Level. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of four samples exceeded the Califonia Toxics Rule standards or the Maximum Contaminant Level and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 21807, Selenium | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5123
Pollutant: | Selenium
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled selenium under the Region 6 SWAMP program in 2001 and 2002. Dissolved selenium concentrations in 3 of 4 samples were below the detection level. The concentration in the remaining sample was an estimated value. The CTR standards were not exceeded.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The California Toxics Rule (CTR) standards for protection of freshwater aquatic life are as follows: 4 day average = 5.0 ug/L; 1-hour average = 20 ug/L.
Objective/Criterion Reference: | Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 21807, Selenium | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7713
Pollutant: | Selenium
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled selenium under the Region 6 SWAMP program in 2001 and 2002. Concentrations of total selenium in 3 of 4 samples were estimated values, and the fourth sample was below the detection level. The MCL was not exceeded.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for selenium is 50 ug/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 20988 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Silver
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the water quality objective. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of eight samples exceeded the applicable water quality objectives and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 20988, Silver | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5064
Pollutant: | Silver
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled silver under the Region 6 SWAMP program. Four total silver samples had concentrations less than 0.05 ug/L, the detection limit. Per listing policy Section 6.1.5.5, the objective is presumed to be attained.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for silver is 100 ug/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 20988, Silver | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5061
Pollutant: | Silver
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological survey sampled silver under the Region 6 SWAMP program. Four dissolved silver samples had concentrations less than 1.0 ug/L, the presumed detection limit. Per listing policy Section 6.1.5.5, the objective and CTR standards are presumed to be attained.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The California Toxics Rule standard for silver (for protection of freshwater aquatic life) is dependent on hardness. At the hardness values reported for this station, the instantaneous maximum standard ranges from 1.34 to 1.77 ug/L
Objective/Criterion Reference: | Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 20824 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Thallium
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the water quality criteria or the Maximum Contaminant Level. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of four samples exceeded the applicable objective or criteria and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 20824, Thallium | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5124
Pollutant: | Thallium
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled thallium. under the Region 6 SWAMP program. Concentrations of total thallium in four samples were all below the detection level. Per listing policy Section 6.1.5.5, the objective is presumed to be attained.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for thallium is 2 ug/L. The California Toxics Rule water and fish consumption standard (for waters designated MUN) is 1.7 ug/L
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 20824, Thallium | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7712
Pollutant: | Thallium
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled thallium under the Region 6 SWAMP program. Dissolved thallium concentrations in four samples were all below the detection limit. Per listing policy Section 6.1.5.5, the objective is presumed to be attained.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The U.S. Environmental Protection Agency's Lowest Observed Effect Levels (LOEL) criteria include an acute toxicity value of 1400 ug/L,and a chronic toxicity value of 40 ug/L. The criteria also include an "Other" limit of 20 ug/L based on 2600 hour exposure of one fish species.
Objective/Criterion Reference: | Quality Criteria for Water 1986. United States Environmental Protection Agency. Office of Water. Regulations and Standards. Washington D.C. EPA 440/5-86-001.
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 20756 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Total Dissolved Solids
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | Regional Board conclusion: This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previouse conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.2 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Three lines of evidence, one to evaluate COLD and one to evaluate MUN, are available in the administrative record to assess this pollutant. None of the 15 samples exceeds the Maximum Contaminant Level for protection MUN. None of the five annual average datapoints exceeds the site-specific objective for protection of COLD. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 15 samples exceeded the California Maximum Contaminant Level. None of 5 annual average datapoints exceeded the site-specific objective and this does not exceed the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains the same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 20756, Total Dissolved Solids | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5053
Pollutant: | Total Dissolved Solids
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 5
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled TDS under the Region 6 SWAMP program at quarterly intervals between 2001 and 2005. Two different laboratory methods were used. TDS concentrations in 15 individual samples analyzed as "residue" ranged from 90 to 186 mg/L. Of two additional samples analyzed as "nonfilterable" , one was below detection level and the other was 11 mg/L. (The "residue" TDS concentration on the same date was 121 mg/L.) There were no violations of the annual average objective in five years of sampling.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The site-specific objective for Total Dissolved Solids (TDS) includes an annual average of 45 mg/L and a 90th percentile value of 160 mg/L (Lahontan Basin Plan Table 3-15).
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Fifteen TDS samples analyzed as "residue" were collected between 2001 and 2005. Two additional samples collected in 2003 and 2004 were analyzed as "nonfilterable."
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 20756, Total Dissolved Solids | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5054
Pollutant: | Total Dissolved Solids
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total Dissolved
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 15
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled TDS under the Region 6 SWAMP program, at quarterly intervals between 2001 and 2005. TDS concentrations in 15 samples analyzed as "residue" ranged from 90 to 186 mg/L. One of two additional samples analyzed as "nonfilterable" had a TDS concentration below detection level; the other sample had a concentration of 11 mg/L. The MCL was not violated.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient surface waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for Total Dissolved Solids (TDS) is 500 mg/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Fifteen TDS samples analyzed as "residue" were collected quarterly between 2001 and 2005. Two additional samples analyzed as "nonfilterable" were collected in 2003 and 2004..
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 21853 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Vanadium
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. There are no applicable standards or criteria for protection of aquatic life. None of the samples exceed the California Notification Level criterion. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of four samples exceeded the criterion and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 21853, Vanadium | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7714
Pollutant: | Vanadium
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled vanadium under the Region 6 SWAMP program. Concentrations of total vanadium in four samples were all below the detection level. Per listing policy Section 6.1.5.5, the criterion is presumed to be attained.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The California Notification Level criterion for vanadium in drinking water is 50 ug/L.
Objective/Criterion Reference: | Drinking Water Notification and Response Levels: An Overview
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 21853, Vanadium | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7715
Pollutant: | Vanadium
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled vanadium under the Region 6 SWAMP program. Concentrations of dissolved vanadium in four samples were all below the detection level. Per listing policy Section 6.1.5.5, the criterion is presumed to be attained.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There are no state or federal standards or criteria for vanadium for the projection of freshwater aquatic life.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 20805 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Zinc
Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | Do Not List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. None of the samples exceed the applicable water quality objective and California Toxics Rule standard. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. 3. None of 8 samples exceeded the applicable objective and California Toxics Rule standard, and this does not exceed the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 20805, Zinc | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5126
Pollutant: | Zinc
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled zinc under the Region 6 SWAMP program in 2001 and 2002. Four total zinc samples had concentrations ranging from below the detection level to 2 ug/L. The MCL was not violated. .
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for zinc is 5000 ug/L. The California Toxics Rule water and fish consumption standard (for waters designated MUN) is 1.7 ug/L
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 20805, Zinc | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5125
Pollutant: | Zinc
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Dissolved
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled zinc quarterly under the Region 6 SWAMP program in 2001 and 2002. Dissolved zinc concentrations in three of four samples were below the detection level and the fourth sample was 2 ug/L. The CTR standards were not violated. .
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The California Toxics Rule (CTR) freshwater aquatic life standards for zinc are dependent on hardness. At the hardness levels reported for this station, the acute (1-hour average) standard ranges from 73.53 to 84.23 ug/L and the chronic (4-day average) standard ranges from 74.13 to 84.92ug/L.)
Objective/Criterion Reference: | Water Quality Standards 2000. Establishment of numeric criteria for priority toxic pollutants for the State of California: Rules and regulations. Federal Register Vol. 65, No. 97. Washington, D.C.: Environmental Protection Agency
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 30425 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Manganese
Final Listing Decision: | List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Sources: | Source Unknown
Expected TMDL Completion Date: | 2021
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: Regional Board Conclusion: This pollutant is being considered for placement on the section 303(d) list under section 3.1 of the Listing Policy. Under section 3.1 a single line of evidence is necessary to assess listing status. Two lines of evidence are available in the administrative record to assess this pollutant. Four of the samples exceed the California Maximum Contaminant Level. Listing is not being recommended because the data are not temporally representative. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used do not satisfy the data quantity requirements of section 6.1.5 of the Policy. Quarterly samples do not capture the full range of seasonal and annual variability expected in streamflows and constituent concentrations in streams of the Lahontan Region. This segment of the East Walker River is also affected by the timing of releases from Bridgeport Reservoir. 3. Four of four samples exceeded the California Maximum Contaminant Level and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. State Board Review and Conclusion: The April 19, 2010 State Water Board staff report for the 2010 Integrated Report recommended to place this water body on the 303(d) list for manganese based on the State Water Board staff determination that the data were collected over a broad period of time to meet section 6.1.5.3 of the Listing Policy. The State Water Board recommendation is based on the following: Lahontan Regional Board staff had decided not to list this water body because staff thought it had insufficient information to make a decision to list. However, State Board staff finds there are 4 samples to make a decision and this meets the sample size requirements of Table 3.1 of the Listing Policy. On August 4, 2010 the State Water Board approved the staff recommendation to place this water body-pollutant combination on the 303(d) list. The final language for the recommendation is: Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. Four of four samples exceeded the California Maximum Contaminant Level and this exceeds the allowable frequency listed in Table 3.1 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 30425, Manganese | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7711
Pollutant: | Manganese
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled manganese under the Region 6 SWAMP program in 2001 and 2002. Concentrations of dissolved manganese in four samples ranged from 11.6 to 36.5 ug/L.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | There are no state or federal standards or criteria for manganese for the protection of aquatic life.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 30425, Manganese | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5085
Pollutant: | Manganese
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | Total
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 4
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey sampled manganese under the Region 6 SWAMP program in 2001 and 2002. Total manganese concentrations in 4 samples ranged from 82 to 119 ug/L. All four samples exceeded the MCL.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The secondary MCL for manganese is 50 ug/L.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four quarterly samples were collected in 2001 and 2002.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):

DECISION ID | 30170 | Region 6
East Walker River, below Bridgeport Reservoir

Pollutant: | Turbidity
Final Listing Decision: | List on 303(d) list (TMDL required list)
Last Listing Cycle's Final Listing Decision: | List on 303(d) list (TMDL required list)(2010)
Revision Status | Original
Sources: | Source Unknown
Expected TMDL Completion Date: | 2021
Impairment from Pollutant or Pollution: | Pollutant
Regional Board Staff Conclusion: | This pollutant was considered for placement on the section 303(d) list in a previous assessment cycle. No new information was reviewed for this current assessment cycle. Therefore, the previous conclusion remains unchanged, and is as follows: Regional Board Conclusion: This pollutant is being considered for placement on the section 303(d) list under sections 3.2 and 3.10 of the Listing Policy. Under section 3.2 a single line of evidence is necessary to assess listing status. Four lines are available in the the administrative record to assess this pollutant. There are no applicable standards or criteria for turbidity expressed as NTU. The Lahontan Basin Plan's narrative turbidity objective, expressed as NTU and used to assess the aquatic life use, is antidegradation based. Sample numbers are insufficient to establish baseline-trend conditions for assessment of compliance with this objective under Listing Policy section 3.10. Nine of the samples expressed as NTU exceed the California Maximum Contaminant Level(MCL). However, listing is not recommended because the data are not temporally representative. Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification against placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used does not satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. Nine of 12 samples exceeded the California Maximum Contaminant Level and this exceeds the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. State Board Review and Conclusion: The April 19, 2010 State Water Board staff report for the 2010 Integrated Report recommended to place this water body on the 303(d) list for turbidity based on the State Water Board staff determination that the data were collected over a broad period of time to meet section 6.1.5.3 of the Listing Policy. The State Water Board recommendation is based on the following: Lahontan Regional Board staff had decided not to list this water body because staff thought it had insufficient information to make a decision to list. However, State Board staff finds there are 12 samples to make a decision and this meets the sample size requirements of Table 3.2 of the Listing Policy. On August 4, 2010 the State Water Board approved the staff recommendation to place this water body-pollutant combination on the 303(d) list. The final language for the recommendation is: Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification in favor of placing this water segment-pollutant combination on the section 303(d) list in the Water Quality Limited Segments category. This conclusion is based on the staff findings that: 1. The data used satisfy the data quality requirements of section 6.1.4 of the Policy. 2. The data used satisfy the data quantity requirements of section 6.1.5 of the Policy. 3. Nine of 12 samples exceeded the California Maximum Contaminant Level and this exceeds the allowable frequency listed in Table 3.2 of the Listing Policy. 4. Pursuant to section 3.11 of the Listing Policy, no additional data and information are available indicating that standards are not met.
Regional Board Staff Decision Recommendation: | No new data were assessed for this assessment cycle. The conclusion reached in the previous cycle remains in same. The Regional Board will update this decision when new data and information become available in a future assessment cycle.

Line of Evidence (LOE) for Decision ID 30170, Turbidity | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5057
Pollutant: | Turbidity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 12
Number of Exceedances: | 9
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey measured turbidity under the Region 6 SWAMP program at quarterly intervals between 2001 and 2004. Turbidity in 12 samples ranged from below the detection level to 12 NTU. The MCL was exceeded in 9 of the 12 samples.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for turbidity is 5 NTU.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Twelve samples reported as NTU were collected quarterly between 2001 to 2004.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 30170, Turbidity | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7717
Pollutant: | Turbidity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey measured turbidity under the Region 6 SWAMP program at quarterly intervals between 2004 and 2005. Turbidity in 4 samples ranged from 2 to 4.2 NTRU.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The applicable objective in the Lahontan Basin Plan states: "Waters shall be free of changes in turbidity that cause nuisance or adversely affect the water for beneficial uses. Increases in turbidity shall not exceed natural levels by more than 10 percent."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four samples reported as NTU were collected quarterly in 2004 and 2005.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 30170, Turbidity | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 5056
Pollutant: | Turbidity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Cold Freshwater Habitat
Number of Samples: | 12
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey measured turbidity under the Region 6 SWAMP program at quarterly intervals between 2001 and 2004. Twelve turbidity samples reported as NTU ranged from below the detection level to 12 NTU.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | The applicable objective in the Lahontan Basin Plan states: "Waters shall be free of changes in turbidity that cause nuisance or adversely affect the water for beneficial uses. Increases in turbidity shall not exceed natural levels by more than 10 percent."
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Twelve samples reported as NTU were collected quarterly from 2001 to 2004.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):
Line of Evidence (LOE) for Decision ID 30170, Turbidity | Region 6
East Walker River, below Bridgeport Reservoir
LOE ID: | 7718
Pollutant: | Turbidity
LOE Subgroup: | Pollutant-Water
Matrix: | Water
Fraction: | None
Beneficial Use: | Municipal & Domestic Supply
Number of Samples: | 4
Number of Exceedances: | 0
Data and Information Type: | Fixed station physical/chemical (conventional plus toxic pollutants)
Data Used to Assess Water Quality: | The U.S. Geological Survey measured turbidity under the Region 6 SWAMP program at quarterly intervals between 2004 and 2005. Turbidity in 4 samples ranged from 2 to 4.2 NTRU. Since the MCL is expressed as NTU these samples cannot be used to assess compliance.
Data Reference: | 2007. SWAMP Data for the West Walker River and East Walker River Hydrologic Units
SWAMP Data: | SWAMP
Water Quality Objective/Criterion: | California Maximum Contaminant Levels (MCLs) apply to ambient waters under the Lahontan Basin Plan's "Chemical Constituents" objective. The MCL for turbidity is 5 NTU.
Objective/Criterion Reference: | Water Quality Control Plan for the Lahontan Region (as amended)
Evaluation Guideline: |
Guideline Reference:
Spatial Representation: | One station, East Walker River at the California-Nevada State Line, was sampled.
Temporal Representation: | Four samples reported as NTRU were collected quarterly between 2004 and 2005.
Environmental Conditions: | The East Walker River is an interstate river, influenced by geothermal springs, agricultural and highway drainage, and releases from Bridgeport Reservoir. Headwater streams originate near the Sierra Nevada crest. The state line is in an area transitional to Great Basin environmental conditions. The segment of the river between Bridgeport Reservoir and the state line supports a trophy brown trout fishery. In addition to the Cold Freshwater Habitat beneficial use, the East Walker River is designated for the Spawning, Reproduction and Development use and the Rare, Threatened or Endangered Species use. The latter designation reflects the watersheds role as habitat for the threatened Lahontan cutthroat trout.
QAPP Information: | Data meet the quality assurance requirements of the SWAMP QAPP.
QAPP Information Reference(s):